Anatomy of the Intrahepatic Ramification of the Portal Vein in the Right Hemiliver

Abstract

The ramification of the portal vein in the right hemiliver was studied by anatomic dissection in 36 formalin-fixed human livers. In 28/36 (77.8%) cases, the portal vein bifurcated into a right branch and a left branch and the right branch bifurcated into anterior and posterior segmental branches. The anterior segmental branch terminated in the anterosuperior subsegment (S₈) in two types: bifurcated when it divided into anterior P₈ and posterior P₈branches towards the respective regions of S₈ (24/28 cases) and monopodal when it had a single pedicle (4/28 cases). The maximum anteroinferior subsegmental branch (P₅maximum) originated either from the anterior segmental branch (16/28 cases) or from the anterior P₈ branch (12/28 cases). The posterior segmental branch vascularized the posteroinferior (S₆) and the posterosuperior (S₇) subsegments, and was terminated in three types: fan-shaped (16/28), bifurcated (9/28) and tripodal (3/28). In 4/36 (11.1%) cases the portal vein bifurcated into a right branch and a left branch but the posterior segmental branch was not present. In 4/36 (11.1%) the right branch of the portal vein was not present. These anatomical variations are explained separately and finally all cases are considered as a whole.

Location of the ventral margin of the paracaval portion of the caudate lobe of the human liver with special reference to the configuration of hepatic portal vein branches

“…This narrow definition is useful in allowing easy differentiation from a PC of right portal vein origin (Kitagawa et al, 2000). Our PV8c seemed to correspond to "PV8 med" in Yamane et al (1988) and Ortale et al (2000) (PV8m in Fig. 1).…”

“…The short portal vein was often due to trifurcation of the anterior and posterior sectorial trunks and the left portal vein, as reported by Inoue et al (1986), Yamane et al (1988), Hata et al (1999), and Ortale et al (2000). Therefore, in that case, identification of the PC originating from the right (or left) portal vein is extremely difficult.…”

“…Because PV5 usually consists of multiple branches, we selected the most superficial one, i.e., the branch nearest the gallbladder bed. Even if there were variations in the portal vein ramification around the right portal bifurcation (Inoue et al, 1986;Yamane et al, 1988;Hata et al, 1999;Ortale et al, 2000), the most superficial PV5 could usually be identified. On the rare occasions when this was not possible, we eliminated the specimen.…”

Human liver caudate lobe and liver segment

“…(2000; 56% in 27 cases) or P8m of Yamane et al . (1988; 96.0% in 25 cases) and Ortale et al . (2000; 45.5% in 33 cases).…”

“…(2001) reported the ‘unusual’ leftward extension of S5 and S8 in the liver parenchymal area above the porta hepatis. However, in recent journals specializing in anatomy and histology, we have found reports of variations of the intrahepatic portal vein ramification according to criteria for the ideal location of the segment such as ‘P5 is defined as a branch to S5’ (Yamane et al ., 1988; Ortale et al ., 2000). This basic concept might eliminate the possibility of S5 being much larger or smaller, or shifted cranially or left, than usual.…”